Question about hats, head size and ribbing

[munchkin928]

Hi all! I am working on the Marsan Watchcap for my hubbie, but I seem to be knitting on a slightly different gauge than the pattern and I had read in the forums that it runs a little small anyways.

I was basically wondering how many inches you would usually subtract off of someone's head circumference if you're knitting them a very stretchy hat (k1p1 twisted rib)? It seems like if I just knitted for the exact circumference of his head the hat would be too loose since it will be so stretchy.

Hope this question makes sense, and thanks for your help.

[Ingrid]

It's usually about 1 inch for a loose fit and 2 inches for a tighter fit.